Exhaled Carbon Monoxide Levels: As a Marker of Clinical Severity and Control of Asthma

Abstract

A study was conducted to evaluate the role of exhaled carbon monoxide (CO) levels in the management of patients with mild and moderate persistent bronchial asthma. Spirometry, exhaled CO measurements and symptom scoring was done before and after four weeks of treatment with inhaled corticosteroids. Exhaled CO levels were significantly elevated in patients of mild as well as moderate persistent asthma as compared to controls but the levels did not correlate with the disease severity. After four weeks of treatment, there was a decrease in exhaled CO levels in both the groups but the decrease was not found to be statistically significant. Therefore, clinically exhaled CO level is not a useful marker in bronchial asthma.

Exhaled carbon monoxide in airway diseases: from research findings to clinical relevance

“…The observed decrease in eCO level after treatment with steroids is consistent with the data demonstrating that corticosteroid therapy inhibits HO-1 enzyme-expression [49,50]. Exhaled CO levels were related with different markers of airway inflammation, airway hyperresponsiveness and asthma control, but the strength of the observed relationships was variable [51][52][53][54][55]. It should be noted that exhaled CO is increased in some atopic adults who are asymptomatic, although to a lesser extent than exhaled NO [56].…”

Medicinal Chemistry and Therapeutic Applications of the GasotransmittersNO,CO, andH2Sand their Prodrugs

“…Today, it is well accepted that CO, similar to NO (see above) and H 2 S (see below), is produced endogenously in a regulated fashion, primarily from the degradation of heme by the heme oxygenase (HO) enzyme system (Fig 12). Endogenous CO formation has been measured in several biological systems; normal human adults have been shown to exhale 12 mL of CO per day, with some reports indicating that the amount of exhaled CO can change in various pathophysiological conditions including acute inflammatory diseases and diseases associated with increased hemolysis [635][636][637][638][639][640][641]. As reviewed in the next section, there are now a multitude of reports demonstrating the important regulatory roles of endogenously produced CO, and the therapeutic effects of exogenously supplied CO in multiple models of disease.…”

Association between exhaled carbon monoxide and asthma outcomes in Peruvian children

“…Characterized as a source of chronic airway inflammation, several markers for inflammation have been considered in detecting the presence of asthma and assessing the degree of asthma control [4]. One of these markers is exhaled carbon monoxide (eCO), which is a potential biomarker among children and adults with asthma [5]. In a 2010 meta-analysis of 18 studies, the weighted mean difference in eCO comparing subjects with asthma and healthy controls was 1.25 ppm (95% CI 0.92-1.58 ppm) [6].…”

“…In a 2010 meta-analysis of 18 studies, the weighted mean difference in eCO comparing subjects with asthma and healthy controls was 1.25 ppm (95% CI 0.92-1.58 ppm) [6]. The mechanism behind this difference in eCO could be the degradation of hemoglobin by the enzyme, heme oxygenase-1 [5]. As hemoglobin is degraded, it promotes the production of CO, which is then exhaled [7].…”

“…In addition to being non-invasive, eCO can be measured using devices that are generally simple to use and affordable, potentially making eCO a feasible asthma control assessment tool in low-resource settings in which access to primary healthcare is limited [5].…”